Subsea fluid processing facility

ABSTRACT

The invention relates to a subsea installation for removing and processing petroleum products such as crude oil and natural gas. The installation includes an under water facility anchored to the sea floor, holding fluid storage tanks as well as processing equipment. The facility is enclosed within a housing and communicated with a source of raw product by way of one or more subsea well heads which provide a continuous flow thereto. The unit further includes a buoyant mast extending upward therefrom, which mast is pivotally connected to said housing and supports conduits for liquid, gas, and electrical conductors which extend to the water&#39;&#39;s surface.

United States Patent Mott [451 Apr. 18, 1972 54] SUBSEA FLUID PROCESSING 3,492,027 1/1970 Herring ..285/315 x FACILITY 3,503,443 3/1970 Blanding et al. ..l66/.6 3,535,883 101970 M ..l66 .5 X [72] Inventor: George E. Mott, Metairie, La. anmng [73] Assignee: Texaco Inc., New York, NY. FOREIGN PATENTS 0R APPLICATIONS 2 June Canada PP 42,405 Primary Examiner Dennis L. Taylor Att0rneyThomas H. Whaley and Carl G. Reis 52 U.S.Cl ..6163 166 .5, 285 315, 1 l 285/520 57 ABSTRACT [51] Int. Cl ..E02b 1/00 The invention relates to a subsea installation for removing and [58] new of Search "61/615146; 285/320 3151 processing petroleum products such as crude oil and natural 285/322; 166/5 gas. The installation includes an under water facility anchored to the sea floor, holding fluid storage tanks as well as [56] References cued processing equipment. The facility is enclosed within a hous- UNITED STATES PATENTS ing and communicated with a source of raw product by way of one or more subsea well heads which provide a continuous 3,366,173 H1968 M nto flow thereto. The unit further includes a buoyant mast extend- 2.938,144 1961 Conrad ing upward therefrom, which mast is pivotally connected to 3,096,999 7/1963 Ahlstone et 285/315 X said housing and supports conduits for liquid, gas, and electri- 3 9 4/1968 Leonard at cal conductors which extend to the waters surface. 3,456,720 7/1969 Brewer .l66/.5 3,472,032 10/1969 Howard ..61/46 6 Claims, 3 Drawing Figures f \l\s a v k m BACKGROUND OF THE INVENTION In the developing and exploitation of offshore sources of gas and oil, it has become necessary to carry the operations to greater depths of water farther from the shore. Usually such sources are drawn from a particular field, or accumulated and carried either by floating vessel or preferably by a pipeline to a shore based refinery for processing. 1

In the raw product drawn from the ground, particularly in the instance of crude oil, much of the bulk product is other than useful petroleum fractions. In the subsequent processing of the material therefore it is initially necessary to separate non-usable as well as gaseous products from the liquid crude. In an offshore installation it is particularly important from an economic consideration, to initially process the raw material. Such a step will serve to avoid costly transfer, whether by vessel or by pipeline, of excessive amounts of non-usable constituents.

Any offshore installation, whether adapted for a drilling or producing operation, and which is located in tidal waters, is continuously subjected to seasonal variations in weather. Particularly in the instance of storms and the like, the offshore installation is exposed to violent winds and turbulent water which have frequently resulted in damage to well equipment and the interruption of output from the facility.

It has become desirable therefore, insofar as practical, to submerge both the well head and subsequent crude oil handling equipment beneaththe waters surface and preferably to the sea floor. This latter circumstance however necessitates the use of divers and other specialized gear particularly adapted for workingat great depths under the sea.

It is one of the objects of the invention therefore to provide an under water facilityfor accumulating and processing crude oil. A further object is to provide a facility of the type contemplated which is adaptedfor continuous remote operation. Still another object is toprovide an under water facility adapted to be remotely monitored and controlled from the waters surface. Still another object is to provide an under water facility which is maintained in contact with the waterssurface by an elongated. flexibly mounted mast which supports utility conduits extending between the surface and the subsea location.

In achieving the foregoing objectives, and toward overcoming the. stated problems, there is presently provided an under water facility for the storage and processing of a fluid such as crude oil. The facility is normally connected to a plurality of submerged well heads at the ocean floor which meter streams of crude hydrocarbon product from underground wells. The facility includes processing equipment which is protected from the subsea environment by a fluid tight housing or enclosure embodying one or more chambers. The facility is further communicated with sources of the crude product as well as with one or more lines for carrying processed fluid from the facility.

The installation, which is normally anchored to the sea floor, is communicated with the waters surface by an elongated mast, buoyantly maintained in an upright position, having the lower end pivotally connected to the housing. The mast upper end extends upwardly of the waters surface a sufficient distance to be beyond the reach of waves experienced under adverse weather conditions. The mast upper end is further provided with means whereby to monitor and control operation of the submerged processing equipment. Said control means affords continuous contact with the subsea facility and permits it to be actuated and regulated from the surface or from a point removed from the installation, as by radio control from a shore based transmitter. The mast also supports utility conductors for air and/or gas whereby to permit regulation of the atmosphere at the facility. In effect, with respect to the submerged equipment the mast functions in one respect as a snorkel tube, allowing the atmosphere to be controlled as to pressure as well as to quality.

The mast is so communicated with the sea floor housing whereby utility conduits and cables extending from the water's surface to the under water facility are disconnectable and can be readily engaged remotely such that the mast can be removed and replaced.

DESCRIPTION OF DRAWINGS FIG. 1 is a side elevation in partial cross-section showing a facility of the type contemplated imbedded in the floor of an oflshore body of water.

FIG. 2 is an enlarged view in partial cross-section showing the lower engaging portion of the mast contemplated, when disengaged from a subsea housing.

FIG. 3 is a view similar to FIG. 1 showing the mast in engaged position with the housing.

FIG. 1 illustrates partially schematically, an under water facility of the type contemplated including necessary processing and storage equipment disposed within a housing 10. While the fluidstorage means such as tanks and the like can be located within an enclosed or protected area, this feature is not essential since said tanks can be disposed equally as well away from the processing equipment and properly anchored to the sea floor. Housing or casing 10 is shown as being spherically shaped. The actual. configuration of said member can be cylindrical, or otherwise to best withstand pressures experienced in the submerged environment.

A conduit 11 communicates well head 12 with crudeoil or gas processing means within housing 10. The latter is connected on the downstream side to one or more conduits 13 which carry processed product to offshore storage facilities or to a shore basedfacility.

Means is further provided for discharginginto the surrounding water, unusable liquids and gases separated from the crude petroleum stream. Said separated components include primarilyunusable gases, sea water, sand and other impurities peculiar to a well effluent.

While the actual equipment used in the processing of the crude oil is not here shown specifically, it is understood that such equipment is substantially equivalent to what would be used on a surface installation providing the same function. For

example, theequipmentincludes such components as pumps,

separators, heat exchangers, manifolds, generators, treaters, etc., all of which are preferably disposed to function within a non-liquid, controlled atmosphere.

Housing 10 formed about said equipment then is preferably of a heavy walled, welded seam metallic structure and pneumatically scalable to withstand externalpressure. The casing thereby forms a fluid tight closure about contained equip ment, which is provided with a controllable artificial atmosphere.

Housing 10 further includes a foundation pad 14 at the lower side which may be fastened to the ocean floor by piles 16, anchors, or by similar appropriate means. Access to the interior of housing 10 is provided through one or more ports such as a manhole 17 which communicates with the fluid tight pressurizable interior. Manhole 17 is further provided with a circular flange or means 18 whereby to sealably engage a service vehicle to afford access to the housing 10 for inspection, removal, or repair of particular equipment.

A collar 19 at the housing upper end supports an anchoring post 22. The latter is characterized by a spherical outer surface adapted to slidably engage a coupling mechanism depending from the mast lower end.

Mast 21 connected at the upper side of the housing 10 is controllably buoyant and removably engages anchoring post 22. Buoyancy means such as one or more internal tanks or compartments 24 and 24' are provided within the mast by water-tight bulkheads 9. Said tanks: are communicated through one or more control lines 26 with the waters surface. A buoyancy system including valves, gauges and other ancillary equipment, is operable from the waters surface to control the attitude of the mast in the water. Mast 21 can assume the form of an elongated cylindrical member extending between the waters surface and the ocean floor. It may however comprise an open structured framework formed of individual structural members which support the various buoyancy tanks and conduits.

For the purpose of the following description, mast 21 will be described as comprising a plurality of structural walled cylindrical members which are end-welded one to the other whereby to form a continuous, elongated passage. The mast, in providing its supporting and communicating function with respect to housing need not maintain fluid tight integrity throughout since individual compartments or members fortning the mast wall will embody this feature.

Mast 21 further carries tracks, brackets, or other suitable means for guidably lowering conduits and connectors through the water, whereby to engage corresponding members at the housing 10. Said conduits and connectors can readily be detachably connected with said corresponding members communicated with said housing and with equipment therein. The conductors mentioned include electrical cables as well as fluid carrying members.

To assure the desired mobility of mast 21 about anchoring post 22, the latter is provided with an arcuate contact surface, having laterally protruding portions preferably in the form of a spherical segment. One embodiment of post 22 comprises a spherical metallic shell fastened at the underside thereof to collar 19 by welding or other appropriate means. The post 22 external contact surface is relatively smooth to slidably accommodate corresponding faces of mast coupling 23. Said anchoring post is further strengthened if need be, by a solid core such as steel reinforced concrete or the like whereby to best withstand varying and cyclical stresses induced in the steel shell of the anchoring post as the result of constant pivotal movement of mast 21.

Connector 23 at the lower end of mast 21 is actuatable between open expanded, and closed retracted positions, by remote control from the waters surface. As seen in FIGS. 2 and 3, connector 23, when in the open position, includes a plurality of inwardly facing jaws or coupling segments 31, disposed about a central actuator 32. The latter includes an uprightly positioned cylindrical body 33 having a concave face 34 at the lower end and a conical shoe member 36 depending from the upper end.

Actuator 32 is supported in the upright position at a constricted neck 37 by a rod or flexible cable or hydraulic cylinder 38, which fastens to ring 39, the control of which is located at the waters surface. Operationally, actuator 32 is vertically adjustable to regulate the disposition of the respective couplings or jaws 31 whether the latter be in the expanded or retracted positions. Biasing means is provided by applying tension to mast 21 as central actuator 32 is released thus causing coupling segments 31 to be forced outwardly by ball connector post 22. Said segments 31 are normally biased into retracted position when actuator 32 is at its lowest point by expendible wire connections 41.

Each segment or connector jaw or segment 31 includes a spherical portion having an inner rubbing surface designed to conform to the corresponding surface of the connector post 22 when in the normally closed position. The rubbing surface of the said spherical segment 31 may be further provided with removable and replaceable wear pads 42 if desired. The pads are adapted to be replaced over a period of time as a result of the pad being abraded away along the outer contoured surface 43. Preferably, coupling segments 31 when in the retracted position, and in lateral engagement one with the other, define at least a portion of a spherical configuration having the center thereof disposed substantially concurrently with the center of the inwardly disposed spherically shaped post 22.

A shank 44 extends upwardly from the spherical portion of the respective jaws 31, terminating at a radially projecting locking tab 46. The outer surface of each segment 31 includes a hub 47 embodying a pivot seat holding a pivot pin 48, which operably couples each segment to the inner wall of a cylindrical casing 49. Said pin connections are disposed peripherally about the casing 49 inner surface to mutually position the respective segments for radial displacement by and about actuator 32.

The lower end of each spherical segment 31 is further provided with an underlip 51 which, together with the contoured inner rubbing surface, forms a bearing contact with the corresponding anchor post 22.

Cylindrical casing 49 depends from the mast lower end and forms a central coupling body. Casing 49 is provided with peripherally spaced pin slide passages 52 which extend through the wall thereof. Each passage 52 is provided with a locking pin 53 slidably received, in said casing, and maintained within passage 52 by a circumferential shoulder 55.

A locking skirt 54 is slidably carried on the outer surface of the casing 49, being longitudinally movable on the latter to dispose said skirt in either the down locked, or raised unlocked position. Eye rings 56 depending from the skirt connect with control cables 57 extending to the waters surface. The latter are remotely actuatable whereby lowering of the cable 57 disposes the said skirt in mutual engagement with the respective spherical segments when the latter are in the retracted position about anchoring post 22.

The inner surface of skirt 54 is provided with an annular, uniformly tapered groove 58, said taper extends from a minimum diameter at the skirt inner wall, to a maximum diameter at the upper end thereof, terminating at a radial seating shoulder 59. When in the retracted position, the forward head 61 of locking pin 52 engages the inner wall of said skirt 54 at a point beneath said annular tapered groove 58. Thereafter, as skirt 54 is lowered into place by control cables 57, pin 56 will be urged radially outward along the tapered surface of said groove 58 to subsequently engage the stop shoulder 59, thereby to support the skirt in desired engagement with jaw segments 31. In such position, the jaw segments 31 are retracted to define a spherical socket within which anchor post 22 is slidably and rotatably received.

Operationally, mast 21 is adapted to be floatably towed, or barged to location and initially lowered to its subsea position in contact with a submerged housing 10. This is achieved by altering the masts buoyancy through the facility of deballasting upper tank 24 while adding a ballast material such as sea water to the lower tanks. As the mast assumes an upright, floating position, further ballasting will cause the unit to controllably descend and eventually engage anchoring post 22.

As the mast is lowered through the water, jaws 31 of coupling 23 are retracted to the position shown in FIG. 2 whereby the respective jaw segments are biased outwardly by expandable wire means 41 to expand the adjustable socket. Skirt 54 is raised to a withdrawn position whereby the respec tive locking pins 53 are urged inwardly through slide passage 52.

As connector 23 is guidably lowered onto housing 10 with the assistance of guide cables 62 and 62 coupling 23 is aligned with the anchor post 22. Such aligning may be further supplemented by the use of auxiliary means such as a derrick barge at the waters surface having the capability of laterally urging the mast into a desired direction for making the required engagement.

When the two members are thus in proper alignment, mast 21 is lowered to a position whereby the under, concave sur face of the actuator 32 comes into abutting engagement with the anchor post 22 upper end. Downward movement of the mast 21 will then urge actuator 32 upwardly, whereby to bring the upper conical surface of body 33 into engagement with the movable shank portions 44 of the respective spherical segments 31. Further upward progression of actuator 32 causes shank 44 to slidably engage surfaces 34, and urge locking tabs 46 outwardly toward the pins 53 against the inward pull of retainer means 41.

Thus, the lower end of the respective clamping segments 31 pivots about pins 48 to close about spherical connector 22 and define a spherical socket. Thereafter, skirt 54 is lowered whereby the inner surface encloses the respective jaws 31 to firmly position the latter in the retracted position. The buoyancy of mast 21 can now be adjusted to maintain a desired upright disposition while avoiding excessive upward pull against the anchor post 22.

Utility conduits 66 and 67 supportably carried on mast 21, as noted are communicated with the interior of housing 10. Said conduits can not only enclose electrical and hydraulic lines, but may also carry gas to and from the housing. Said gases function to maintain a controlled atmosphere within housing or within discrete portions thereof. Further, usable and waste gases separated from the hydrocarbon stream can readily be conducted to the waters surface for disposal or further storage.

As shown in FIG. 1, one such gas conducting system includes rigid conduit 66 and 67 carried on the inner wall of mast 21, extending from a point above the waters surface to the mast lower end thereof. Conduit 66 for example, terminates at an automatic coupling 68 positioned externally of the mast. Said coupling is sealably and detachably engaged to corresponding coupling member 69 which is in turn communicated with a conductor 71. The latter enters housing 10 by means of collar 19 to be directed thence to a point of use. It is appreciated that because of the virtually continuous move ment of the mast in response to displacement by the water, the respective conductor portions 66 and 71 are preferably communicated by a flexible form of coupling at 68 and 69, that can readily adjust to such movement and yet maintain the fluid tight integrity of the connection.

Obviously many modifications and variations of the invention, as hereinafter set forth, may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the ap pended claims.

lclaim:

1. In an underwater facility positioned in an offshore body of water, and being adapted to process hydrocarbon fluids communicated with said facility from a source of said fluids, which facility includes;

a. a housing fixedly positioned at the floor of said body of water enclosing equipment for processing said hydrocarbon fluids, and an anchor post extending upwardly from 6 said housing,

b. an elongated mast including buoyancy means therein for urging the mast into a vertical attitude when said mast is submerged in said body of water, and

c. coupling means disposed at the lower end of said elongated mast, being actuatable between expanded and contracted positions to slidably engage said anchoring post whereby to permit limited pivotal movement of said mast about said housing,

d. and means to remotely actuate said coupling means for releasably engaging said respective housing and mast.

2. In a facility as defined in claim 1 wherein said coupling means includes; a segmented jaw including a plurality of circularly arranged jaw segments, the latter being pivotally connected to said mast end, and adapted when in the expanded position to be spaced from said anchor post, and when in the contracted position to slidably engage the latter whereby to permit said pivotal movement between said mast and said housing.

3. In a facility as defined in claim 1 including; a skirt operably carried on said mast, being movable between extended and retracted positions, when in the extended position, said ring engaging the outer surface of said coupling when the latter is in the contracted position, whereby to maintain said segmented jaws in sliding engagement with said anchor post.

4. In a facility as defined in claim 1 including; an actuator disposed centrally of said coupling, means having a portion thereof normally in engagement with said jaw segments, said actuator being horizontally movable to urge said respective jaw segments into the contracted position about said anchoringpost for slidably ertigaging the latter. I

. In a facility as de med in claim 1 Including; biasing means engaging said coupling means whereby to normally urge said jaw segments into the expanded position whereby to disengage said anchoring post.

6. In a facility as defined in claim 4 wherein said actuator includes; a tapered upper section disposed in engagement with said segmented jaws, and a lower face adapted to engage said anchor post whereby lowering of said mast onto said anchor post will bring said actuator face end into contact with said anchoring post thereby to urge said jaw segments into the contracted position about said post. 

1. In an underwater facility positioned in an offshore body of water, and being adapted to process hydrocarbon fluids communicated with said facility from a source of said fluids, which facility includes; a. a housing fixedly positioned at The floor of said body of water enclosing equipment for processing said hydrocarbon fluids, and an anchor post extending upwardly from said housing, b. an elongated mast including buoyancy means therein for urging the mast into a vertical attitude when said mast is submerged in said body of water, and c. coupling means disposed at the lower end of said elongated mast, being actuatable between expanded and contracted positions to slidably engage said anchoring post whereby to permit limited pivotal movement of said mast about said housing, d. and means to remotely actuate said coupling means for releasably engaging said respective housing and mast.
 2. In a facility as defined in claim 1 wherein said coupling means includes; a segmented jaw including a plurality of circularly arranged jaw segments, the latter being pivotally connected to said mast end, and adapted when in the expanded position to be spaced from said anchor post, and when in the contracted position to slidably engage the latter whereby to permit said pivotal movement between said mast and said housing.
 3. In a facility as defined in claim 1 including; a skirt operably carried on said mast, being movable between extended and retracted positions, when in the extended position, said ring engaging the outer surface of said coupling when the latter is in the contracted position, whereby to maintain said segmented jaws in sliding engagement with said anchor post.
 4. In a facility as defined in claim 1 including; an actuator disposed centrally of said coupling, means having a portion thereof normally in engagement with said jaw segments, said actuator being horizontally movable to urge said respective jaw segments into the contracted position about said anchoring post for slidably engaging the latter.
 5. In a facility as defined in claim 1 including; biasing means engaging said coupling means whereby to normally urge said jaw segments into the expanded position whereby to disengage said anchoring post.
 6. In a facility as defined in claim 4 wherein said actuator includes; a tapered upper section disposed in engagement with said segmented jaws, and a lower face adapted to engage said anchor post whereby lowering of said mast onto said anchor post will bring said actuator face end into contact with said anchoring post thereby to urge said jaw segments into the contracted position about said post. 